Abstract:

We sought to assess the effects that oil exposure would have on the growth and survival of Juncus roemerianus, the dominant species in Alabama coastal salt marshes. J. roemerianus sod was collected from salt marshes in Mobile Bay, and mesocosms were established at Auburn University. Louisiana sweet crude oil was weathered for 0 days, 3 days, and 3 weeks, and applied in high, medium, or low concentrations to each of the mesocosms, resulting in three mesocosms with each treatment. J. roemerianus was assessed after two, four, and ten weeks for culm heights and counts, photosynthesis, and carbon assimilation. We found the low dose mesocosms had highest culm survivorship and photosynthetic activity. Although differences observed between oil weathering treatments were not significant, those treated with unweathered oil consistently had the lowest culm survivorship and photosynthetic activity. Publication citation: Anderson, C.J. and T.A. Hess. 2012. The effects of oil exposure and weathering on black-needle rush (Juncus roemerianus) marshes along the Gulf of Mexico. Marine Pollution Bulletin 64(12):2749-2755

Suggested Citation:

Anderson, Christopher J., and Thomas A. Hess. 2015. Dataset for: The effects of oil exposure and weathering on black-needle rush (Juncus roemerianus) marshes along the Gulf of Mexico.. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N70Z7178

Publications:

Anderson, C. J., & Hess, T. A. (2012). The effects of oil exposure and weathering on black-needle rush (Juncus roemerianus) marshes along the Gulf of Mexico. Marine Pollution Bulletin, 64(12), 2749–2755. doi:10.1016/j.marpolbul.2012.09.015

Purpose:

The goals of this project were to increase understanding of the effects of oil exposure and help characterize the sensitivity of these wetlands for improved management decisions when oil spills occur. The objectives of this study were to 1) better understand how high exposure rates would impact salt marshes dominated by J. roemerianus, 2) better understand what kind of response J. roemerianus would have to high oil exposure, and 3) test if weathering would have an effect on oil impacts.

Data Parameters and Units:

Mesocosm # (number), Dose [None, Low, Medium, High], Total petroleum hydrocarbon soil concentrations (mg/g dry soil), individual culm photosynthetic rates (µmol CO2/m^2/s), J. roemerianus culm counts, J. roemerianus culm heights (cm), estimated carbon accumulation rates (g C per mesocosm h^-1).

Methods:

Soils: Two samples were randomly taken from each mesocosm in July and October. A knife was used to cut two 2 cm x 10 cm soil cores. The Florida residual petroleum organic method was used to determine total petroleum hydrocarbons (TPH). We ran a paired t-test and found there to be no statistically significant difference between concentrations in July and October. Culm Counts and Heights: For each mesocosm, at two weeks prior to exposure, and two, four, and ten weeks after exposure, culms counts were conducted, number of live and dead culms were recorded, and heights of ten randomly selected live culms were measured. Photosynthetic Activity: Photosynthetic activity was measured before and after oil exposure. 2-3 healthy culms were gathered, placed in a LiCor chamber with 400 ppm ambient CO2 concentration and red-blue LEDs set at 1,000 µmol m-2 s-1, and CO2 concentrations were taken halfway down the stem. Carbon Assimilation: Net C assimilation was estimated by multiplying total surface area by average measured photosynthetic rate and dividing it by the grams of carbon per mesocosm per h. ((Number of live culms)*(mean culm length)*(2.5π [culm circumference based on 2.5 median culm diameter])*(photosynthetic activity in µmol CO2 mesocosm-1 s-1))/(g C mesocosm-1h-1)

Instruments:

LiCor 6400XT Portable Photosynthesis System

Error Analysis:

A linear two-way analysis of variance (ANOVA) was run on all treatment types, and where statistically significant differences were found, a Tukey’s pairwise comparison test was conducted.

Individual Files: